Design a transaction class for deposits/withdrawals

Design a Transaction/Account component that supports deposits and withdrawals.

Assume you are building a backend library or service used by other parts of a financial application.

Requirements

• Maintain an account balance .
• Support operations:
  • deposit(amount)
  • withdraw(amount)
  • getBalance()
• Record a transaction history (at minimum: id, type, amount, timestamp, status).

Constraints / edge cases to handle

• Amount must be positive.
• Prevent the balance from becoming negative (or clearly define overdraft rules).
• Handle concurrent requests safely (e.g., two withdrawals at the same time).
• Ensure operations are atomic and leave the account in a consistent state.
• (Optional, if time) Support idempotency so retrying the same request doesn’t double-charge.

Explain your design choices, data structures, and how you would test it.